Arizona Sen. Jeff Flake says Donald Trump needs to issue specific apologies to Sen. John McCain, the judge in the Trump University lawsuit, and to Mexican immigrants.

Trump, reading from prepared remarks on Thursday, expressed regret for the first time ever for causing “personal pain” by saying “the wrong thing."

Flake, who has said he cannot support Trump, added that he wanted to back him, but said the Republican nominee would need to change his positions on a number issues.

"It's a step in the right direction, I'm not part of the 'Never Trump' movement, I want him to change," Flake said on KFYI radio on Friday. "I just know that unless he does change, not just the tone and tenor of the campaign, that has to change certainly, but some of his positions need to change as well. If he can do that, then he can win. Let's take what he said yesterday, he apologized for not always being artful in his delivery."

"I think it would do more good for him to say, 'hey, I disparaged John McCain and his service by saying, I only respect those who weren't captured. I'm sorry for that. 'That was the wrong thing to say, and I respect John McCain,'" Flake said. "'I referred to a judge born in Indiana as a Mexican in pejorative way. I'm sorry for that. I shouldn't have. I shouldn't have implied that he can't judge fairly because of his heritage. I referred early in my campaign to Mexicans who cross the border as rapists. That was a broad brush and I'm sorry because I did offend people.'"

"That would go a long way, I'm glad he started, I hope he continues, but some of the positions need to change as well," he added, citing Trump's Muslim immigration ban, trade policy, immigration policy, and position on NATO.

Flake also said that Trump's supporters need to stop chanting 'lock her up' in reference to Hillary Clinton, saying it damages their credibility and is similar to those who claim President Obama was born in Kenya.

"If he can go after those policy differences and silence his supporters and others who are simply saying 'lock her up.' Once you say that, you're just dismissed in terms of credibility," Flake said. "It's like going after Barack Obama's positions but by starting saying, 'he was born in Kenya, he's not really legitimately our president.' If you want credibility you can't start off like that. You have to go after the real policy positions where she has had problems. And there are plenty of them."